opposition to proposed ordinance: technical/scientific elements on behalf of – pavement coatings...
TRANSCRIPT
Opposition to Proposed Ordinance:
Technical/Scientific Elements
On Behalf of – Pavement Coatings Technology Center
Robert P. DeMott, Ph.D., DABTEnvironmental Toxicologist
Addendum (slides 2-7) G.C. Dubey, STAR, INC.
CITY OF AUSTIN (COA) passed a ban on the use of coal tar sealants, effective Jan. 1, 2006
COA reached the following conclusions:
• High concentrations of Polycyclic aromatic hydrocarbons (PAH’s) are present in sediments within the Austin waterways.
• Primary source being the parking lots sealed with coal tar sealers.
• Ban on coal tar sealers will significantly change water quality and protect organisms in the streams.
PCTC STRONGLY DISPUTES COA’s FINDINGS:
REASONS
1. The COA Study is incomplete. It did not conclusively prove that PAH,s found in the sediments.
2. Current publications on urban sources of PAH’s (including USGS’s publications) do not support COA’s conclusions.
3. Overall PAH’s levels in sediments in Austin are NOT high relative to other cities- USGS stated after the ban.
PCTC STRONGLY DISPUTES COA’s FINDINGS
4. All PAH’s sources and contribution should be quantitatively examined for COA’s claim.
5. 2800 lbs. (1300 kg) of PAH are produced by COA traffic is 130 times greater than PAH’s from water run off from parking lots. – EPA & Texas transportation Institute.
6. Risks are greater for alternative sealer i.e. asphalt based sealer (A/E) will abrade and deteriorate faster.
PCTC STRONGLY DISPUTES COA’s FINDINGS
7. COA did not consider asphalt based sealers as a source of PAH’s.
8. Adverse Economic Impact, using a less durable product (A/E) was not considered by COA.
PCTC’s RESPONSE & ACTION PLAN
1. GET ALL THE DATA ON AUSTIN STUDIES (under Texas Open records Act.)
2. Article in Feb/March issue of Pavement magazine- PCTC’s position, and critique on Austin’s FUZZY science.
3. PCTC’s own PAH studies on Sediment sampling & Source characterization, and national publication & presentation.
PCTC’s RESPONSE & ACTION PLAN
4. Toxicological research- Bio-availability of coal tar sealer particles and the specific effects on sediment dwelling amphibians and invertebrates.
5. Challenge USGS’s findings (“formal request for corrections” procedure.
6. Keep a tab on the PAH noise in Washington- a consultant will monitor.
7. Tell our side of the story- Hire a Public Relations (PR) firm.
Overview
Scientific evaluation incomplete
Current publications contradict anticipated benefit of ordinance
Specific comparison sources and PCTC sediment study should be considered
Substitution risk should be specified quantitatively
CITY OF AUSTIN (COA) passed a ban on the use of coal tar sealants, effective Jan. 1, 2006
Based on studies by:
• COA’s Watershed protection & Development Review dept. (WPDRD)
• United Sates geological Survey (USGS)
Background -- PAHs Are Everyday Urban Constituents
From all combustion processes
- Vehicle exhaust and power generation unchallenged
predominant urban sources overall
Present in construction materials
- Asphalt pavement; roofing; pavement sealers
Used in consumer products
- Shampoos; dyes; medicines; plastics; mothballs
All chemicals are toxic –managing exposure differentiates “pollution” from dandruff control
“The presence and distribution of PAHs in the environment are largely a product of the incomplete combustion of petroleum, oil, coal, and wood. Anthropogenic sources such as vehicles, heating and power plants, industrial processes, and refuse and open burning are considered to be the principal sources to the environment.”
Van Metre, Mahler and Furlong, 2000. Urban Sprawl Leaves its PAH Signature. ES&T 34: 4064.
Vehicles in Austin Emit More Than A Ton of PAHs/Year
USEPA -- PAHs in vehicle exhaust 3.7 x 10-7 pounds/mile
Texas Transportation Institute -- 20.8 million miles traveled per day in Austin
Exhaust contributes 2800 pounds (1300 kg) per year of PAHs
U.S. EPA. 1998. Locating and Estimating Air Emissions from Sources of Polycyclic Organic Matter
Texas Transportation Report. 2005. The 2005 Urban Mobility Report.
Shampoos and Topical Gels
Denorex Shampoo
- 12.5% coal tar solution for
dandruff control
- Each bottle contains 5400
mg of PAH
- Product contains “percent
levels” of PAHs, yet environ-
mental loading managed, not
perceived to pollute
Austin Waterbody PAH Levels Not Extraordinary
Sediment measurements typical – sources: Van Metre et al., 2000. ES&T 34:4064; Geismer report. COA unpubl. results.
0
50
100
150
200
250
Co
nc
. (m
g/k
g)
State of Science
USGS/City team published report documenting coal tar constituents can be washed off coal tar-based pavement sealer
City presented unpublished results on:
- aquarium testing of midges, scuds
- General stream quality around parking lots
No specific analysis of proportionate input from various PAH sources
USGS/City 2005 Study
Mahler, Van Metre, et al. 2005.Parking lot sealcoat: An unrecognized source of urban polycyclic aromatic hydrocarbons. ES&T 39:5560
Determined PAH amount washed from coal tar pavement sealer
Identified PAHs in runoff from in-use parking lots
Could NOT detect different PAH input from coal tar sealer vs. asphalt sealer in-use lots
Recent Study Results
Average PAH yield -- first 3 washings of freshly sealed pavement is 0.046 mg/m2
Mahler, Van Metre, et al., 2005 -- Table S-2
For residential driveway (540 sf) = 2.3 mg
After three simulated rainfall events, average yield drops 10-fold to 0.004 mg/m2
Mahler, Van Metre, et al., 2005 -- Table S-2
City-wide, amounts to 9.8 kg of PAH per year85 rain events, 2% of area as freshly sealed lots
PAH Content from Various Sources (mg)
2187000
111000
2000
2.3 2.3
0.12
5400
0.1
1
10
100
1000
10000
100000
1000000
10000000
Road asphaltbinder (per mile
of road)
Quart usedmotor oil
12 oz. bottle ofDenorex
Vehicle exhaust(12,000
miles/year)
Coal tar sealeddriveway -- 1st
rain event
Rooftoprunoff/rain event
Mesquite-cooked burger
Source Type
PA
H C
on
ten
t (m
g)
Sources of PAH Contributions Equivalent to Rain Event on
Freshly Sealed Residential Driveway (50m 2)
2.7 2.3 2.5 2.3 2.3
0.1
1
10
100
1000
10000
100000
1000000
10000000
1 eyedropper dropused motor oil
3 eyedropper dropsDenorex shampoo
Exhaust from 15 milesof road travelled
Coal tar-sealeddriveway
Rooftop (~1800 sfhome)
PA
H C
on
trib
uti
on
(m
g)
Source: Mahler, Van Metre et al. 2005
Source: Van Metre &Mahler 2003
Eyedropper
Drop
Used
Motor Oil
Auto Exhaust
15 mi.
3 Drops
Denorex
Sealer
Washoff
Driveway
1800 sf
Home
Rooftop
Runoff
Sources of PAH Contributions Equivalent to Rain Event on Freshly Sealed Commercial Lot (1 Acre)
267 225 190 190 171
0.1
1
10
100
1000
10000
100000
1000000
10000000
1 teaspoon used motoroil
1/2 oz. Denorexshampoo
5 seconds of vehicleexhaust in Austin traffic
One-acre coal tar-sealedparking lot
2 large retail buildings(200,000 sf)
PA
H c
on
trib
uti
on
(m
g)
Source: Mahler, Van Metre et al.
2005
Source: Van Metre &Mahler 2003
1 tsp
Used
Motor Oil
½ oz.
Denorex
5 sec. -
Austin
Vehicle exhaust
Sealer
Washoff
1 acre
lot
2 large
Retail
Rooftops
Runoff
Limits of 2005 USGS Study
No comparison to:
- previously measured PAH loading settling from air
- rooftop runoff to drainage features
No specified proportions of overall PAH loading to waterways
Not challenging value/validity of study, these elements simply not included
Beyond Study Findings
Following cited to substantiate pavement sealer releasing “majority” of PAHs to environment
“The average yield of PAHs from sealed parking lots is 50 times greater than that from unsealed lots. PAH assemblages and estimated loads further suggest that sealed parking lots could be dominating PAH loading in watersheds with commercial and residential land use.”
Mahler, Van Metre, et al., 2005. Parking Lot Sealcoat: An UnrecognizedSource of Urban PAHs. ES&T 39:5560
No mention of non-parking lot input
No data to support suggestion –“This issue needs a lot more research.” P. Van Metre, 16 November 2005, Society for Environ. Tox and Chem
Unpublished Aquarium Tests
Selected doses well above known lethal levels – outcome pre-determined by design
Not yet meet scientific standards requiring description of materials used
- Source of test material not disclosed
- Verbal description of sealer “turning to powder” inconsistent with normal properties
- Lack of full chemical characterization precludes repeat by others
Unpublished Stream Surveys
Parking lot/roadway drainage contains many chemicals besides PAHs- Example: Copper from brake linings highly toxic
to stream life – subject of other research groups
Reductions in stream quality routinewith urban drainage
Drought/scour cycles wash outmany Austin creek stretches
Urban Stream Impacts Already Established
USGS documented non-sealer PAH and metal runoff sufficient to impact stream quality
“Concentrations of zinc, lead, pyrene, and chrysene on a
mass per mass basis in a majority of rooftop samples
exceeded the established sediment quality guidelines
for probable toxicity of bed sediments to benthic
biota…. Metal roofing was a source of cadmium and
zinc and asphalt shingles a source of lead.”
p.1741; Van Metre and Mahler 2003. Chemosphere 52:
1727.
Benefit Projection Contradicted by Other Research
“Based on the USGS (United States Geological Survey) study it's pretty apparent that these sealants, particularly the coal tar sealants, are dumping a large portion, probably the majority of the PAHs that we see in the Austin area” – News 8 report, 9 Nov 2005
2005 USGS study does not mention fallout from air and other PAH sources
Previous publications by same USGS research team, however, measured other contributions larger than projection from coal tar sealer
Airborne Transport Measured
Van Metre & Mahler, 2003. The Contribution of Particles Washed from Rooftops to Contaminant Loading to Urban
Streams. Chemosphere 52: 1727-1741.
- Roofs receive 9.2 g/m2 PAH from air
- Percentage of watershed covered by roofs measured from
aerial photos
City-wide – 261 kg of PAHs wash off roofs per year
26X more than washoff from freshly sealed pavement
Airborne Contribution to Lots
Applying USGS airborne settling rate (9.2 g/m2)
- Austin parking lot area = 39 kg/yr PAH from air
4X more than washoff of freshly sealed lots
- Austin street/sidewalk area = 41 kg/yr PAH from air
4X more than washoff of freshly sealed lots
Tire Wear49%
Coal Tar Sealer
Washoff1%
Airborne Fallout to
Streets6%
Airborne Fallout to
Parking Lots6%
Rooftop Runoff
38%
Sealer Washoff Contributes Less Than 1% of PAH Loading
Preliminary, “on paper” analysis indicates need for direct measurement and follow-up.
Major Sources Not Included:
•Used Motor Oil
•Gas station runoff
•Pavement Debris
•Paved banks/ drainage channels
Traffic, Not Urbanization Drives PAH Levels
USGS study of Town Lake concluded:
- “increases in PAHs are proportional to increases in
vehicle traffic”
- “The large increases in traffic offer an explanation
for why PAHs more than doubled in Town Lake
from 1975 to 1990 while percent urban land use
only increased by 5%.”
Source: Van Metre, P.C. et al., 2000. Urban Sprawl Leaves Its Signature. ES&T
34:4064.
Total PAH Increases in Town Lake Coincide with Increase in Vehicle Miles Traveled
Source: Van Metre, Mahler and Furlong. 2000. ES&T 34: 4064 – 4070.
Substitution Risk Requires Analysis
“No Free Lunch…”
More asphalt sealer –
- wears faster
- USGS study did NOT detect a difference in PAH loading from
in use asphalt-sealed lots vs. coal tar-sealed lots
No Sealer
- more pavement debris
- penetration of petroleum-soluble contaminants